Welding device



C. L. GREEN WELDING DEVICE Oct. 25, 1960 2 Sheets-Sheet 1 Filed Oct. 10,1958 Clifton L G r g gg 2 4 ATTORNEYS.

Fig. 2.

Oct. 25, 1960 c. L. GREEN 2,957,976

WELDING DEVICE Filed Oct. 10, 1958 2 Sheets-Sheet 2 Clif'ron L. Gg een,daxhz ATTORNEYS- Patented Oct. 25, 1960 WELDING DEVICE Clifton L. Green,608 Hereford Drive, Athens, Ala. Filed Oct. 10, 1958, Ser. No. 766,628

4 Claims. (Cl. 219-81) (Granted under Title 35, US. Code (1952), sec.266) Theinvention described herein may be manufactured and used by orfor the Government for governmental purposes without the payment of anyroyalty thereon.

. My invention relates to a machine for spot welding pairs of lappedplates and more particularly to contact wheels for such a machine.

Spot welded lapped joints are limited to A1. inch total thickness, andthe spaced welds are required to meet specifications stipulating thatwelds between those of such plates having equal thicknesses shallinclude nuggets projecting 50% into each of the plates, and that weldsbetween such plates of unequal thickness shall include nuggetsprojecting into the thinner plate 20% of the thickness thereof, and intothe thicker plate 80% of the thickness thereof. The depressions in theplates accompanying the welds are required by the specifications to besubstantially circular and to penetrate the plates less than .003 inch.

The specifications further require that the plates be free from stainscorresponding to the weld nuggets. The electrodes of the welding machineare respectively provided with journaled wheels for contact with therespective plates and it has been determined that such stains are causedby pickup by the wheels of the material of certain plates and redepositof the material in oxidized form on the surfaces of the plates at thewelds.

In commercial welding, such stains are disregarded. To overcome thestrains for material required to meet the specifications noted above,metallic plates are designated in Classes I, II, and III with respectiveweldability characteristics comparable to those of the materials,aluminum, carbon steel and stainless steel and wheels of difierentcopper compositions are customarily employed for welding plates of therespective classes.

Recommendations of the American Welding Society include complicatedspecifications for pairs of electrode wheels within the classes to meetthe various combinations of composition, thicknesses and hardness in theplates. Although commercial machines are provided with facilities formany intricate combinations of pressure and current cycles, completeequipment of such a machine for welding all of the combinations ofplates within the inch range of total thickness would include some 200pairs of wheels or substantially a pair of wheels for each of thecombinations. An average machine is provided with approximately 54 pairsof wheels, entailing considerable storage facilities for each machine.The wheels are currently priced at substantially $700 per pair, and therequirement of frequent changes in machine setups entails high operatingcosts of the machines.

It is an object of my invention to provide a pair of contact wheels fora welding machine to perform the entire spot welding functions of themachine.

Another object of my invention is to provide such a machine with suchpairs of the wheels provided with compositions corresponding to theclasses of plate mate rial.

Other aims and objects of my invention will appear from the followingdescription.

In carrying out my invention, tests of spot welds revealed that thecharacter of the welds in the range below inch total thickness issubstantially independent of the diameters of the contact wheels. Platesin the thickness range were spot-welded with pairs of wheels havingunequal edge radii of 2 inches to 20 inches. Of all of the combinationstested, the only combination that succeeded in lap-welding all thecombinations of thicknesses of plates within the range, in conformancewith the specifications, included wheels with edge radii of 4 inches and8 inches. In welding pairs of plates of unequal thickness the 4" wheelwas disposed for contact with the thinner plate.

To eliminate staining of the welded plates, similar pairs of the wheelswere constructed of the usual compositions corresponding to the classesof material.

For more complete understanding, reference is directed to the followingdescription and the accompanying drawing, in which,

Fig. 1 is a view of the electrodes of a welding machine incorporating anembodiment of my invention;

Fig. 2 is an enlarged sectional view through the welds;

Fig. 3 is a View along line 33 of Fig. 2;

Fig. 4 is a view along line 44 of Fig. 2;

Fig. 5 is a view of the electrodes including a pair of wheels forWelding plates of non-uniform thickness; and,

Pig. 6 is a view along line 6-6 of Fig. 5.

Accordingly, a machine 12, for securing lapped portions of plates 14together With spaced welds 16 is provided with electrodes 18, and a pairof wheels 20 and 22 disposed for selective journaled engagement with theelectrodes.

As shown in Fig. 3, plates 24 and 26 are of equal thickness 28 andwheels 20 and 22 are rounded and provided with edge radii 30 and 32 forrespective engagement with the plates. In plates of equal thickness,machine 12 is required to produce nuggets 36 of welds having portions 38respectively projecting into 50% of thickness 28. The nuggets arerespectively accompanied by depressions 42 disposed in the surfaces ofthe plates and the depressions are required by the specifications to besubstantially circular as shown in Fig. 4. The greatest allowable depth44 of the depressions is .003 inch.

Wheels 20 and 22 having edge radii 30 and 32 of 4 and 8 inchesrespectively were found to produce nuggets 36 and depressions 42 withinthe specification for all of the equal plate thicknesses within therange.

Wheels 20 and 22 as shown in Fig. 5 are disposed for joining a pair ofplates 50 and 52 having unequal thicknesses 54 and 56 respectively toproduce spaced weld nuggets 58 with portions 68 and 70 of substantially20% and respective penetration into the thicknesses of the respectiveplates. The depth 72 of depressions 74 corresponding to welds 58 wasfound to be within the maximum depth of .003 inch allowable in thespecification.

Intervals between Welds 16 may be reduced for overlapping thereof toproduce a pressure proof continuous weld between plates 14 with similarpenetration of the welds in the equal and unequal depth plates.

Similar wheels were constructed of the compositions customarily employedfor welding plates in the material classes noted above to produce weldswithin the specification for staining.

While the foregoing is a description of the preferred embodiment, thefollowing claims are intended to include those modifications andvariations that are within the spirit and scope of my invention.

I claim:

1. In a machine disposed to produce spaced weld nuggets between lappedportions of metallic plates and provided with a pair of electrodes; apair of wheels disposed for respective journaled engagement with theelectrodes and provided with rounded edges having complementary unequalradii of curvature for respective engagement with thelapped portions toproduce therein substantially circular depressions and accompanyingnuggets with penetrations thereof in the respective plates correspondingto the thicknesses thereof.

2. A pair of Wheels as in claim 1 with said complementary radii havingrespective values of substantially 4 inches and 8 inches to limit themaximum depth to the depressions of .003 inch; for penetrations of thenuggets into plates of equal thickness, 50% thereof; and for tiveengagement with said wheels for operation of the machine to producespaced circular depressions in the respective plates, and correspondingnuggets therebetween having penetrations in the plates corresponding tothe thicknesses thereof.

4. A process as in claim 3 with the wheels of said pair respectivelyprovided with 4 inch and 8 inch edge radii for respective engagementwith plates of the pairs thereof having equal thickness for penetrationof the nuggets therein; respective engagement with the thinner and otherplates of the pairs having unequal thicknesses for 20% and respectivepenetration therein; and for corresponding circular depressions in allof the plates limited to a depth of .003 inch.

References Cited in the file of this patent UNITED STATES PATENTS1,264,058 Geisenhower Apr. 23, 1918 1,522,993 Alexander Jan. 13, 19251,583,906 Von Henke May 11, 1926 1,862,108 Brueckner June 17, 19322,684,424 Anderson July 20, 1954

